Male-female morph interactions in the damselfly Nehalennia irene (Hagen)

Several hypotheses concerning factors that favour coexistence of female morphs in damselflies (Zygoptera: Odonata) invoke differential attraction to (or harassment of) female morphs from mate-searching males. We designed experiments to determine whether males were differentially attracted to either of two discrete female morphs in a damselfly, Nehalennia irene (Hagen). One female morph was similar in colour and pattern to the conspecific male ("androchrome") and the other was dissimilar ("gynochrome"). Males were indiscriminate in their mating attempts. Overall, males were more attracted to gynochrome females; however, males that showed high response intensity to model males were equally likely to grasp models of the gynochrome and androchrome females. During male–female encounters in the field, androchrome females were more likely to chase males, whereas gynochrome females showed more refusal displays. Other direct and indirect evidence suggests that gynochrome females may be greater targets of sexual aggression than androchrome females while at the pond's edge, but that androchrome females more often frequent the pond's edge. Whether or not these differences in behaviour translate into differential costs and benefits of being a particular morph is unknown.